The present invention relates, in general, to a method for obtaining DNA samples using an adhesive sheet and, more particularly, to a method for obtaining DNA samples from human epidermal scraps which are taken with the aid of an adhesive sheet. Also, the present invention is concerned with combined sheets for storing DNA and with a kit for obtaining DNA from the epidermal scraps.
The genetic material DNA (deoxyribonucleic acid) constitutes the genes encoding the synthesis of cellular components and metabolisms of all creatures. The great advances of life science in the latter half of the 20th century, including the Genome Project, predicts the generalization of genetic analysis.
As a consequence of the Genome Project, human beings are able to read all of the genetic information of human DNA and the genes responsible for or involved in hereditary diseases have been discovered one after another. In addition, genetic abnormalities are now comprehended in a nucleotide sequence level. Accordingly, knowledge of gene types involved in diseases will allow potential patients to take appropriate precaution as well as enable doctors to give appropriate prescription and treatment.
Since DNA is ubiquitous in every cell and DNA type is discriminable between individuals, there have been developed genetic identification (or DNA profiling) methods which can discern individuals from one to another at a gene level. By virtue of its accuracy, the genetic identification technique is regarded as the best tool in fields such as forensic tests and paternity tests. In practice, in the U.K. and the U.S., DNA profile databases for prisoners have been constructed and used to examine suspects with the aid of computers by comparing DNA profiles obtained from evidences obtained from the scenes of crimes.
Whether it is used for disease diagnosis or genetic identification, DNA is usually obtained from blood. Blood sampling for DNA profile, however, is problematic for the following reasons:
First, blood sampling should be conducted by specialized workers, such as doctors or nurses.
Second, testees suffer discomfort upon the blood sampling.
Third, there always exists the possibility of blood handlers being infected with diseases, such as hepatitis or AIDS.
Fourth, blood sampling may be unobtainable on account of age, health, religion, etc.
Fifth, blood sampling is associated with cumbersome problems. In this regard, because direct identification of testees is impossible only by blood samples taken from testees, their photographs and fingerprints should be taken to assure the reliable match of blood donors with testee, and relevant samplers, carriers, and analyzers make out the chain of custody documents. For example, the FBI of the U.S.A. has established a guideline such that anyone and all who are involved anywhere in the chain of custody sign or otherwise witness such involvement including those carrying and handling blood samples. Assurance is made double in marking blood samples (Technical Working Group on DNA Analysis Methods, xe2x80x9cGuidelines for a quality assurance program for DNA analysisxe2x80x9d Crime Laboratory Digest, 22:21-43, 1995).
Sixth, compulsory blood sampling for executing laws is adjudged to be against the Constitution in the U.S.A. (Lehrman, Nature 394:818, 1998).
In order to overcome such inconveniences, an attempt has recently been made to use mouth epithelial cells instead of blood. The mouth epithelial cells have advantages over blood samples in various aspects. However, similar complicated procedures, documents and witnesses as in the case of blood sampling are needed in order to assure the reliable match of a sample donor with a particular testee. In addition, the sampling of epithelial cells within the body causes the testee to show reluctance to it.
The intensive and thorough research on genetic identification, repeated by the present inventors aiming to overcome the conventional problems occurring upon the sampling of blood or oral cells, resulted in the finding that the epidermis could be an ideal source for DNA and that DNA materials could be obtained from epidermis at a sufficiently large amount for DNA analysis by use of an adhesive sheet with an advantage of not taking other separate identification measures. That is, when DNA is obtained from the epidermis of the fingers, the palms, the foot soles or the toes by use of adhesive sheets, sufficient amounts of DNA are reserved on the adhesive sheets, together with fingerprints, palm prints, footprints or toe prints, which allow the donors of DNA samples to be always discerned individually without taking photographs and utilizing other identification procedures. Since the epidermal scraps attached on the adhesive sheet of the present invention are in a dry state, the DNA in the scraps can be stably conserved for a long period. Together with the prints printed on the adhesive sheet, DNA profiles which are obtained from the epidermis attached to the sheet can be used for the identification of unknown corpse, paternity test, investigation on hereditary diseases, etc.
Therefore, it is an object of the present invention to overcome the above problems encountered in prior arts and to provide a method for obtaining DNA, by which both DNA sampling and the identification of a testee can be performed simultaneously.
It is another object of the present invention to provide a means for obtaining or storing DNA samples from individuals or a population.
In one aspect of the present invention, there is provided a method for obtaining human DNA by taking the epidermis of a testee by means of an adhesive sheet and by extracting DNA from the epidermis stuck on the adhesive sheet.
In another aspect of the present invention, there is provided a method for genetic analysis using human DNA, comprising the steps of taking epidermal scraps from the skin of a testee by use of an adhesive sheet; visualizing the epidermal print as an image; recording the image in an optical or electronic medium; extracting DNA from the epidermal scraps stuck on the adhesive sheet; and measuring physical and chemical properties of the DNA.
In a further aspect of the present invention, there is provided combined sheets for taking the epidermis or for storing DNA, comprising an adhesive sheet and a protective sheet for protecting an adhesive surface of the adhesive sheet.
In still a further aspect, there is provided a kit for taking epidermal scraps or for extracting DNA, comprising the combined sheets for taking the epidermis or for storing DNA.